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ExprNullValue.java
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ExprNullValue.java
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/*
* Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.amazon.opendistroforelasticsearch.sql.data.model;
import com.amazon.opendistroforelasticsearch.sql.data.type.ExprCoreType;
import com.amazon.opendistroforelasticsearch.sql.data.type.ExprType;
import java.util.Objects;
/**
* Expression Null Value.
*/
public class ExprNullValue extends AbstractExprValue {
private static final ExprNullValue instance = new ExprNullValue();
private ExprNullValue() {
}
@Override
public int hashCode() {
return Objects.hashCode("NULL");
}
@Override
public String toString() {
return "NULL";
}
public static ExprNullValue of() {
return instance;
}
@Override
public Object value() {
return null;
}
@Override
public ExprType type() {
return ExprCoreType.UNDEFINED;
}
@Override
public boolean isNull() {
return true;
}
@Override
public int compare(ExprValue other) {
throw new IllegalStateException(
String.format("[BUG] Unreachable, Comparing with NULL is undefined"));
}
/**
* NULL value is equal to NULL value.
* Notes, this function should only used for Java Object Compare.
*/
@Override
public boolean equal(ExprValue other) {
return other.isNull();
}
}